Production of dull lacquer finishes



Patented Sept. 26, 1950 TI'UNITED STATES PATENT OFFICE PRODUCTION OFDULL LACQUER FINISHES Alan Dowbiggin, Lancaster, England, assignor toStorey Brothers and Company Limited, White Cross Mills, Lancaster,Lancaster, England No Drawing. Application January 21, 1948, Se-

rial No. 3,547. In Great Britain February 6,

. Hitherto in the preparation of dulling lacquers a nitrogen content (asN2) of 12.3% or less dissolved in a suitable solvent, and another ofpoly- 2 vinyl butyral dissolved also in a suitable solvent; or asolution of nitrocellulose as previously referred to, to which thepolyvinyl butyral resin is added in the dry form followed by a suitablefor the dulling of artificial leathercloth and the 5 solvent. The formermethod I refer to as the like or more rigid bodies, it has been usual totwo solution method and the latter as the dry utilise a nitrocellulosesolution in which was solution method. In the case of the twosoludispersed Opaque matter of small particle size, tion method I findit convenient to have the suitably ground if necessary, such aspigments, nitrocellulose solution of not greater than 35% ochres, earthsor salts such as aluminum stearate solid content, and that of thepolyvinyl butyral and the like. Each of these presented particular notless than 10% solid content in order to endifficulties usuallyassociated with dispersion and sure the particle size of theprecipitated nt s ab y, a d i s k ow ha a improvement cellulose beingsmall and uniform. The solutions upon the aforementioned ochres, earthsand the are mixed together with constant stirring until like can beobtained by precipitation of, an homogeneous, alcohol-insolublenitrocellulose in an essentially In the case of the dry solution methodI prefer alcoholic solution of an alcohol-soluble nitrothat thenitrocellulose solution be less than cellulose giving y such meansdulling lacquers. solid content but the solid content of each or From te industrial point of view, however, this any of the solutions may bevaried as desired method sufiers from the defect of being difficult 20within wide limits. to control and in addition since the nitrocelluloseIn either case the mixture is further diluted which constitutes thecontinuous phase is the with alcohol which acts as a precipitating agentalcohol-soluble variety, it is necessarily of the for thealcohol-insoluble nitrocellulose, and is low nitrogen type and,therefore, gives a film then ready for application. which does notpossess the tensile strength which I th following examples I give thepropormight be desired. tions in a typical case for the preparation of aThe object of t e p esent invention is to produll lacquer containinrespectively an alcoholde a dull lacquer finish Which l not Sufferinsoluble nitrocellulose and an alcohol-soluble from any of thedisadvantages referred to above it llm d Which y be more easily preparedh n The term alcohol soluble nitrocellulose gent known finishes. erallyunderstood to cover one having a nitrogen e invention consists in amethod of produccontent falling between the limits 10.5 to 11.2 g a ulacquer finish by miXinB Solution per cent, and the term alcoholinsoluble nitronitrocellulose with a solution Of a Suitable resincellulose to cover one having a nitrogen content Soluble in alcoholaqueous alcoholof 11.8 to 12.3 per cent. The alcohol insoluble Theinvention also consists in method nitrocellulose are readily soluble inesters and cording to the preceding paragraph which the ketones buttheir solubility in alcohol is low. resin employed is a modlfiedpolyvmyl acfital The alcohol soluble nitrocellulose ,is soluble in Suchfor example as those known as Polyvmyl weaker solvents containing muchmore alcohol butyral and acetate- 40 than the alcohol insolublenitrocellulose grade. According to the invention the nitrocelluloseReferences to the alcohol Soluble and the employed. may be either thealcohol'soluble or cohol insoluble nitrocellulose are intended, therethealcohol-insoluble nitrocellulose, and the fore, to imply a degree oftolerance to alcohoL method of procedure difiers somewhat according towhich is used. In either case I obtain in the EXAMPLE I resultinglacquer film a dispersion of discrete particles of nitrocelluluose whichbeing opaque solution A or semi-opaque, constitute the dulling agent. 25parts by Weight nitrocellulose When using alcohol-solublenitrocelluloses I need 25 parts by Weight acetone only add a proportionof water to the alcohol 0 efiect precipitation of the nitrocellulosewithout 50 parts by welght mdustnal spmts afiecting, however, thestability of the polyvinyl Solution B butyral. In carrying my inventioninto effect I either Egg: x322? prepare two solutions, one ofnitrocellulose known as industrial nitrocellulose, that is, having 5parts by weight of Solution A are mixed with parts by weight of SolutionB in a convenient mixing machine of standard type and diluted 3 with 100parts by weight or more or less of industrial spirits serving as aprecipitating agent.

EXAMPLE II Solution A parts by weight nitrocellulose 25 parts by weightacetone parts by weight industrial spirits Solution B 25 parts by weightpolyvinyl butyral parts by weight industrial spirits parts by weight ofSolution A, are mixed with parts by weight of Solution B in a convenientmixer of standard type and diluted with 50 parts by weight of industrialspirits and 3. parts: by weight of water serving as a precipitatingagent.

In the following example the nitrocellulose is of the same type as inExample I.

EXAMPLE III 25 parts by weight nitrocellulose 18.75 parts by weightacetone 56.25 parts by weight industrial spirits To this solution isadded with-constant stirring:

14 parts by weight polyvinyl butyral 42 parts by weight industrialspirits When solution is completed 60' parts by weight of industrialspirits are added serving as a precipitating agent;

Should it be desired to make a more pliable dull lacquer it is merelynecessary to add the desired quantity of softener such as:

Castor oil Tri-cresyl phosphate Di-butyl phthalate Butyl Cellosolvephthalate to Solution B in the first two examples and to the completedsolution in- Example III. The amount of softener can be varied from 5%upwards but it is not found desirable to add more than 50% on thecombined nitrocellulose/polyvinyl butyral content.

The lacquer may be applied by spreading, spraying, or other methodnormally employed by those skilled in the art of leatherclothmanufacture, and in the application of the lacquer the method is notrestricted to an embossed specimen of leathercloth, that is to say, itmay be applied to a leathercloth on which a design has been impressedor, alternatively, it may be applied to unembossed', that is, plainleathercloth, the latter being embossed subsequently as desired withoutdetriment to the dullness of the lacquer.

It will also be understood'that the proportions of the variousingredients given above are by way of example only, and that my improvedlacquer may be applied to materials other than leathercloth.

I claim:

1. In the preparation of dull lacquers, the process which comprisespreparing a homogeneous solution in an alcohol containing solvent ofnitrocellulose and an alcohol-soluble polyvinyl acetal resin, and addinga precipitating agent for the nitrocellulose to produce a dispersion ofdiscrete particles of nitrocellulose.

2. The process of claim 1 wherein the said homogeneous solution isprepared by mixing solutions of the nitrocellulose and the polyvinylacetal resin.

3. The process of claim 1 wherein the said homogeneous solution isprepared by dissolving the polyvinyl acetal in a solution of thenitrocellulose.

4. In the preparation of dull lacquers, the process which comprisespreparing a homogeneous solution in an alcohol-containing solvent ofnitrocellulose and an alcohol-soluble polyvinyl resin selected from theclass consisting of polyvinyl acetate and polyvinyl butyral and adding aprecipitating agent for the nitrocellulose to produce a dispersion ofdiscrete particles of nitrocellulose.

5. The process of claim 4 wherein the nitrocellulose is analcohol-insoluble nitrocellulose and the precipitating agent employed isalcohol.

6. The process of claim 4 wherein the nitrocellulose is analcohol-soluble nitrocellulose and the precipitating agent employed iswater.

7. The process of claim 4 wherein the nitrocellulose employed is onehaving a nitrogen content of not exceeding 12.3 per cent. I

8. The process of claim 4 wherein a softener is added in the amount offrom 5 to 50 per cent by weight based on the combined weight of thenitrocellulose and polyvinyl acetal.

9. In the preparation of dull lacquers the process which comprisespreparing a homogeneous solution in an alcoholic solvent ofnitrocellulose and polyvinyl butyral, and adding a precipitating agentfor the nitrocellulose to produce a dispersion of discrete particles ofnitrocellulose.

10. In the preparation of dull lacquers the process which comprisespreparing a solution in an alcoholic solvent of a nitrocellulose havinga nitrogen content not exceeding 12.3 per cent by weight, said solutionhaving a concentration of nitrocellulose not exceeding 35 per cent byweight, preparing a solution of polyvinyl butyral in an alcoholicsolvent containing not less than 10 per cent by weight of polyvinylbutyral, mixing the two solutions and adding a precipitating agent forthe nitrocellulose to produce a dispersion of discrete particles ofnitrocellulose.

ALAN DOWBIGGIN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,293,558 Overholt Aug. 18, 1942FOREIGN PATENTS Number Country Date 14,583 Australia Aug. 23, 1934502,670 Great Britain Mar. 20, 1939

1. IN THE PREPARATION OF DULL LACQUERS, THE PROCESS WHICH COMPRISESPREPARING A HOMOGENEOUS SOLUTION IN AN ALCOHOL CONTAINING SOLVENT OFNITROCELLULOSE AND AN ALCOHOL-SOLUBLE POLYVINYL ACETAL RESIN, AND ADDINGA PRECIPITATING AGENT FOR THE NITROCELLULOSE TO PRODUCE A DISPERSION OFDISCRETE PARTICLES OF NITROCELLULOSE.